The fact of making recommendations about treatments demands for a systematic analysis of the different variables involved. The direction of these variables will become a recommendation into a strong one, when the benefits outweigh the harms, or into a weak one, when profits and losses are balanced. In this way, evidence based medicine analyzes this variables: 1) the quality of the literature; 2) the importance of clinical effect; 3) the magnitude of the effect; 4) the risks of the disease to treat; 5) the risks of treatment; 6) the costs; 7) the preferences of the patients; 8) the inconvenience to patients; 9) the minimum and maximum effect and 10 ) if the recommendation is strong or weak. This ten steps strategy will lead us to the construction of a scientifically based recommendation.